Manufacture of felt



Patented June 17, 21930 MdNUFAGTURE @F FELT Our invention relates to the treatment of animal fibres, such as wool, cows hair, etc., in preparation for its manufacture into felt, It has been developed in the treatmentofc' fur, and in that application we shall describe it. The objects in view are improvement in the quality of the product, reduction in the cost of production, and avoidance'of manufacturing conditions such as to afiect the to health of operatives. The preponderant use for fur felt is in the making of hats.

Tt has long been known that by boiling in dilute nitric acid, with. the addition of a small quantity of grease, the felting property of fur may be improved; the felting operation may be expedited. About the year 1725 the discovery was made that if, before removal from the pelt, the far be brushed with a dilute solution of nitric acid and mercuric nitrate, the felting properly of the fur may be more greatly improved. The reagents so applied afi'ect primarily and chiefly the extremities of the hairs, and incidentally cause them to become discolored. Because of the discoloration, the treatment is called carroting. It is a treatment which has continued in commercial use to the present day.

There are objectional features of the carroting treatment. The discoloration of the fur, which in'the manufacture of white and light-colored felts is particularly undesirable, may be avoided only by the exercise of great care; the best results are obtained by holding this -i'ur at least a month after treatment, to age, before being used in hat-making, and such delay is undesirable; furthermore, inequalities in periods of aging tend to result in lack of uniformity in quality; the mercury salt is expensive, and its provision adds much to the cost of hat-making; the mercury present in the form' and quantity and under the conditions of operation requires great sanitary precautions attendant on its use. Nevertheless, the industry has Application flied li eceniber 19, 1923. Serial No. 327,1?8.

of these obj ecbreak up, with the production of an acidic or an alkaline solution, and particularly if the so broken-up components be a weak base and a strong acid, and if the fur be then subjected to the action of steam under pressure, feltmg property in still greater'degree may be imparted to it.

The efifecfiwe have discovered, is that of hydrolysis. It may be gained by subjecting the fur to the action of steam under pressure, no other agent being present. The effect is, however, intensified if another agent be present. If that other agent be the solution of nitric acid and mercuric nitrate knownto the art, the steam treatment permits the use of a weaker solution with which to brush the fur. There is gain then in saving of material and in the fact that the precautions which must be taken when mercury is used are less burdensome; and there are the further gains, that the tendency to discoloration is diminshed, that aging is no longer necessary, and that better uniformity of product is attained.

Preferably we employ a solution of a salt or salts other than salts of festing the tendency which we have mentioned, the tendency to break up in the presence of water. A suitable saltpf the character indicated is chloride of magnesium; another is chloride of aluminum; another is ferric nitrate. The common characteristic which these salts possess of breaking up in mercury manithe presence of water into a weak base and a strong acid will be recognized by the chemist. And other salts having the same characteristic will lie fairly within his knowledge and contempation. Which salt will be chosen, among those will depend on practical considerations. We have indicated particular salts which, generally speaking, are practically avallble. Other salts which break up into a strong base and a weak acidsodium, acetate, sodium phosphate, and'sodium bi-carbonate, for examplesmay be used, though we prefer salts of the class first mentioned.

It is possible to use, instead of a solution of asalt, a solution of an acid alone or of a basealone, subjecting the fur, when application of the solution has been made, to the action of steam under Kressure, as in the preferred procedure. nd, as has been explained, the fur may,-without preliminary application to it'of any solution, be sub ected 1mmediately to the action of steam underpressure." a The procedure in which our invention resides may be-carried out typically as follows.

- The fur while'still on the pelt is brushed with nesium; the pelt is a one-normal'solution of chloride of magdried; the fur is removed from the elt; and then, within an autoclave, it i s-for t e period of an hour and a half subjected to the'action of steam at a pressure of 20 pounds. Being then dried and removed from the autoclave, the fur isready for the feltin operation.

We ave given the steam pressurewhich we have found to be convenient to use, and the time which we have found to be requisite for pressure, of (say) twenty pounds, is fully eration which in every 'givenby way of example.

treatment at that pressure. These figures are The invention is practiced in treatment with steam under pressure, and the time requisite for treatment will vary as the pressure varies, being greater if the pressure be less.

The operation is one which, under a steam an hour and a half;

accomplished in about no period of aging is required. It is an opdetail and circumstance may be' minutely able.

to it ias been conducted,

The fact has been recognized that similar classes of fur, prepared in similar manner,

may have different felting properties. This to wet thorou hl g y will in felt manufacmethod here described theoretlcally available,

controlled; and, in f consequence, uniformity of product is atta1n-' wets easily.

In the practice of our invention, the steam treatment effects sterilization of the material, and this manifestly is a desirable condition.

In the practice of our invention, while we may use a solution of a mercury salt, we are not under the necessity of doing so, and preferably we do not employ such a solution. Thus we may wholly avoid the necessity of taking sanitary precautions such as have been alluded to; we avoid also the relatively great cost of a mercury salt. We avoid those variations in thequality of mercury-carroted fur which are due to variations in times of aging. In the practice of our invention the tendency of the fur to ored is diminished, and in the operation as we preferto conduct it that tendency completely disappears. The fu after treatment does not require aging, but may be used at once; and, as we have said, since the operation is susceptible to exact control, it is capable of not. r We have described the removal of the in from the pelt before subjecting it to the action of steam under pressure in the autoclave.

affording a uniform prod become yellow or otherwise discol- It is permissible to subj ect-the fur while still on the pelt to the steam treatment, and afterward to remove the fur. Alternatively, it is possible first to cut the fur from the pelt, immerse it in the solution, dry it, and then subject it to the steam treatment; or, it may when out from the pelt be subjected immediately to the steam treatment. It will be understood that the method may in practice be modified in such details.

The felt roduced in the practice of our invention ta es dye in more uniform-manner than does felt hitherto produced.

Our treatment with scribed has practical value in the preparation of fur for felting. 'It is applicable, with like effect, to animal fibre of other particular kinds; to cow hair, for example, and to wool. Cow hair may be used as a filler in felt making, and when cow hair is to be so used, we recommend that it be treated in the manner described.

We claim as our invention:

1.v The method of preparing animal fibre for felt-making which consists in subjecting it to the action of steam under pressure, together with an acidic hydrolytic agent.

2. The method of preparing animal fibre for felt-making which consists in subjecting it to steam under pressure, together with a substance which in the presence of steam affords acidic reaction.

3. The method of preparing animal fibre for felt-makin which consists in subjecting 'it to steam un er pressure, together with a 4. The method of preparing animal fibre the advantages deand I meapee for felt-making which consists in sub'ecting it to steam under pressure, together wit chloride of magnesium.

5. The method herein described of prepar- 6 ing fur for felt-making which consists in brushin the fur while still on the pelt with a. salt wich in the presence of steam under Eressure afl'ords acidic reaction the ur, and subjecting it to the action of steam m under pressure.

In testimony whereof we have hereunto set 1 our hands.

* GEORGE D. BEAL.

ROB ROY MOGREGOR. 

